Sitegrounds Pushing Trouble

Me and the company I'm working for has run into a bit of a predicament when it comes to pushing one particular website. We've given a client of ours access to the staging site so they can add events and content and push without me or my boss needing to intervene when they need a push. However, there's been an issue as of lately that prevents any kind of push from succeeding.

A month ago our client came to us to report an issue with the pushing functionality. What had appeared to have happened was that every time a staging site is pushed live, a backup is created in case you need to roll back. Repeated pushes will make these backups (3 gb a piece) take up space in our account and rapidly close in on the 30 gb limit our account has. This prevented the staging site from being pushed live, and caused the push to fail because the backup couldn't be created with such little space remaining. What we ended up having to do was delete the backups that had accumulated, thus allowing the push again.

Fast forward to today, the same thing ended up happening as a month or so ago. Client tries to push, can't because disk is too full. So I go in and delete the backups like last time to make space, and it ends up getting stuck yet again at the same backup creation process despite there being ample space on the disk. Something clearly is amiss here, so I immediately went to Siteground support to figure out what was going on. After a lengthy discussion with support, they told me that there was some kind of a plugin issue that was breaking the push function. "tar: wp-content: file changed as we read it" is the error the tech told me he received, which basically says a plugin was supposedly updating information to the live site while the push was occurring, creating a discrepancy in wp-content that cancelled the push.

I'm not entirely certain what kind of plugin would cause this error and was hoping that some of you would have some more insight as to what could be the culprit, but earlier today I found something that might be a clue. We're using The Events Calendar PRO for our site, and earlier someone seemed to update it on the live site according to the log, which for some reason ended up breaking the site. I disabled the plugin to bring the site back online, thinking that plugin could cause an issue with the pushing, but it ended up not helping matters at all when I disabled it on the staging site and tried to push. So now that I have it narrowed down to a potential plugin issue, has anyone on this forum had issues like this with plugins interfering with staging sites and pushing?